Adaptable Single Active Loop Thermal Control System (TCS) for Future Space Missions

This low-TRL study concerns the development of a versatile and reconfigurable active Thermal Control System (TCS) for future multi-mission spacecraft. The proposed system will be capable of tackling widely varying heat loads and both cold and warm environments, while improving system performance, reducing weight and volume, and ensuring reliable operation irrespective of gravitational field. These goals will be accomplished using an environmentally friendly refrigerant/coolant by enhancing the thermal performances of the TCS evaporators and condenser. The objectives of this study are related to the following NASA Technical Areas and associated Space Technology Roadmaps. Primary: TA14 Thermal Management Systems Secondary:TA03 Space Power and Energy StorageTA06 Human Health, Life Support and Habitation Systems
Consolidated database for two-phase pressure drop in TCS evaporators A new universal technique was developed to predict the frictional pressure gradient for saturated flow boiling. To both develop and validate the new technique, a consolidated database consisting of 2,378 data points was amassed from 16 sources. The database consists of 9 working fluids, hydraulic diameters from 0.349 to 5.35 mm, mass velocities from 33 to 2,738 kg/m2s, liquid-only Reynolds numbers from 156 to 28,010, qualities from 0 to 1, reduced pressures from 0.005 to 0.78, and both single-channel and multi-channel data. The new correlation was shown to be far superior in accuracy to all prior correlations. 
Consolidated database for two-phase heat transfer coefficient in TCS evaporators
A consolidated database for flow boiling in small channels was amassed from 31 sources, of which 10,805 data points correspond to pre-dryout conditions. The pre-dryout database consists of 18 working fluids, hydraulic diameters of 0.19- 6.5 mm, mass velocities of 19-1608 kg/m2s, liquid-only Reynolds numbers of 57-49,820, qualities of 0-1, and reduced pressures of 0.005-0.69. The new correlation was shown to be far superior in accuracy to all prior correlations.
Modeling of film flow in TCS condensers
Efforts have been made to develop a theoretical foundation for modeling thin film transport behavior in TCS condensers. This effort addressed the complex influences of waves and interfacial dampening of turbulent eddies on fluid flow and heat transfer. 
Critical heat flux (CHF) in TCS evaporators This task investigated the interfacial phenomena preceding the occurrence of CHF for flow boiling with a finite inlet vapor void. Understanding these phenomena is crucial to maintaining safe operation of TCS evaporators.
Gravity effects on flow boiling
This task involved performing experiments to explore the complex mechanisms associated with flow boiling inside the evaporators of a TCS as a result of reduced gravity. A key focus of the study is the occurrence of critical heat flux (CHF) in the evaporators when the fluid is supplied as a two-phase mixture. 
Thermodynamic analysis of TCS
This task was focused on thermodynamic analysis of the adaptable TCS, which can accommodate one-phase (1Φ), two-phase (2Φ), and heat pump (HP) operating modes. 
Preliminary TCS facility
This task involved constructing a preliminary TCS facility to assess the influence of R134a vapor compression on transport behavior in the crew and avionics evaporators. 
Determination of dominant heat transfer mechanisms in evaporators 
This task involved using the preliminary TCS facility to assess the influence of R134a vapor compression on transport behavior in the crew and avionics evaporators.